need to know if a girl is prettiest than me

Noone gives a damn how you look - Most folk are far too busy admiring/loathing their own appearance - To consider yours, unless you are humpable, marketable or of aesthetic use to them.
Beauty is far from superficiality.

In the first place, it's wrong for you to compare yourself with anybody else - especially your looks. You are the product of all your ancestors - which, BTW, you had no control over. Beauty is in the eye of the beholder. Attraction is very subjective; not objective. It has to do with physical appearance to be sure, because that's the first attraction, but that isn't what makes relationships last.
Mothers always believe their baby is the most beautiful in the world when born.